A page from a 15th century book entitled Imago Mundi (Image of the World).
This book was written in 1410 by French scholar Pierre d'Ailly and published in
1480. From the annotations which appear in the margins of this page, it is known
that Christopher Columbus read this copy before embarking on his 1492 voyage.
Asserting that the Atlantic Ocean was relatively narrow, d'Ailly wrote that it
'was not so great that it can cover three quarters of the globe.' This shows
that most people believed the earth to be a sphere. D'Ailly's book was one of
the scholarly works which encouraged Columbus in his belief that the shortest
route to Asia was to the west.